The aim of this career development award is to become an independent investigator in patient-oriented research involving children with chronic kidney disease (CKD). The prevalence of pediatric end stage renal disease (ESRD) is 86.1/million. Despite the low prevalence, pediatric CKD carries significant morbidity and mortality. The expected remaining lifetime for a child, 0-14 years of age and on dialysis is only 20 years. The focus of research in pediatric CKD should be identification of risk factors for progression. Chronic Kidney disease in children (CKiD) is a prospective cohort study of kidney disease in children and adolescents aged 1-16 years. The aims of this epidemiologic study are to determine the risk factors for progression of chronic kidney disease and its effects on cardiovascular health, growth and neurocognitive development. Low vitamin D levels have recently emerged as a potential risk factor for CKD progression, because of their association with higher blood pressure and albuminuria.FGF-23 is a novel hormone that is a negative regulator of 1,25 dihydroxy vitamin D levels and has been shown to have an association with mortality in adult ESRD patients. For the initial part of the research proposal, data from the CKiD study will be used to determine the prevalence and correlates of 25 hydroxy vitamin D (25OHD) and 1,25 di hydroxy vitamin D [1,25(OH)2D] deficiency. A questionnaire will be developed to assess the intake of 25OHD from nutritional and environmental sources. Prevalence and correlates of 25OHD deficiency will be compared between the CKiD cohort and age and race matched controls in the NHANES 2001-2004 database. We propose to measure the levels of 1,25 (OH)2D and FGF-23 hormones in the CKiD population. The associations of 1,25 (OH)2 D with the progression of CKD and growth delay will be determined. The last part of our study will examine the determinants of FGF-23 and explore its role in the dysregulation of vitamin D hormone axis, progression of CKD and growth delay in pediatric CKD. My determination to have a successful career in research started with obtaining a Master's degree in Public Health and the K23 grant will further help me to acquire skills necessary to fulfill my aim of becoming an independent clinical investigator. PUBLIC HEALTH RELEVANCE: End stage renal disease is a world wide epidemic. There is an urgent need to find novel risk factors that would delay progression and improve outcomes in CKD. This K-23 study proposal aims to elucidate the role of novel risk factors for chronic kidney disease progression in one of the most vulnerable population to be afflicted by this disease.